Distributed antenna system using power-over-ethernet

ABSTRACT

A system is provided for adjusting power provided over a channel to a device. The system can include power sourcing equipment and a sub-system. The power sourcing equipment can provide power to a powered device via a channel. The sub-system can determine an amount by which to increase the power based on a resistance of the channel. The power sourcing equipment or the powered device can adjust the power (or load) in response to a command from the sub-system. The sub-system can include at least one measurement device and a processor. The measurement device can measure an output voltage of the power sourcing equipment, an input voltage of the powered device, and a current on the channel. The processor can determine the resistance of the channel based on the output voltage, the input voltage, and the current. The processor can output a command specifying an increase or decrease in the level of power supplied by the power sourcing equipment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/506,934 filed Oct. 6, 2014, which is a continuation of U.S. patentapplication Ser. No. 13/491,849 filed Jun. 8, 2012, which claimspriority to U.S. Provisional Application Ser. No. 61/495,067 filed Jun.9, 2011, all of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to telecommunications and moreparticularly (although not necessarily exclusively) to a method andsystem for delivering power over Ethernet cables.

BACKGROUND

Numerous powered devices utilize power over multi-pair Ethernet cables.The IEEE 802.3at-2009 Power-over-Ethernet (“PoE”) standard, ratifiedSep. 11, 2009, defines a standardized approach for providing power overEthernet cables.

A non-limiting example of an Ethernet cable is a category 5 cable. Acategory 5 cable includes eight wire connectors grouped into four wirepairs. Under the IEEE 802.3at-2009 PoE standard, power sourcingequipment can provide DC power over two of the four wire pairs includedin the cable. Such pairs are generally referred to as a PoE powered pairor powered cable pair. Power can be injected into the powered cablepairs of a cable using Ethernet magnetics in a pair of PoE taps. A “pairof PoE taps” refers to the center taps of two of the four wire pairs inan Ethernet cable.

In PoE systems, one tap of a pair of PoE taps is used for power deliveryand a second tap is used for power return. The power is injected intothe center tap of the Ethernet transformer of one of the twisted pairsin the powered cable pair. The return is extracted at the center tap ofthe Ethernet transformer of a second twisted pair of the power cablepair. Direct current (“DC”) power can be provided over the powered cablepairs as a common mode current. Telecommunications systems can utilizethe pairs in the cable as data lines. Data can be provided over one ormore wire pairs as a differential signal. In some systems, power anddata may be provided on the same twisted pair. The Ethernet devicereceiving the power and data via the Ethernet cable can include adifferential input that suppresses the bias and noise associated withthe common mode current. As a result, providing DC power as a commonmode current reduces the interference to the data signals.

Under the IEEE 802.3at-2009 PoE standard, power sourcing equipment canprovide a powered device with up to up to 25.5 watts of DC power over,for example, a category 5 twisted pair communication cable. Astelecommunications devices adapt to meet new communication demands,however, such devices may have different power needs or demands. Forexample, as more functionality is added to communication devices andsystems, such devices and systems may include powered peripheral devicesthat couple with or are plugged into the main communication devices.Such peripheral devices may need more than 25.5 watts of power.

Accordingly, a versatile system and method for providing PoE power tocommunication devices in a wireless communications system is desirable.

SUMMARY

In some aspects, a system is provided that includes power sourcingequipment and a sub-system. The power sourcing equipment can providepower to a powered device via a channel. The sub-system can determine,based on a resistance of the channel, an amount by which to increase alevel of power provided to the powered device. The power sourcingequipment can adjust the level of power by the amount in response to acommand from the sub-system.

Another aspect is a system that includes at least one measurement deviceand a processor. The measurement device can measure an output voltage ofthe power sourcing equipment, measure an input voltage of the powereddevice, and measure a current on the channel. The processor candetermine the resistance of the channel based on the output voltage, theinput voltage, and the current. The processor can output a command tothe power sourcing equipment to increase the level of power and theamount by which to increase the level of power.

Another aspect is a system that includes a powered device, powersourcing equipment, a channel, and a sub-system. The power sourcingequipment can provide power to the powered device. The channel cancouple the power sourcing equipment to the powered device. Thesub-system can include at least one measurement device and a processor.The measurement device can measure an output voltage of the powersourcing equipment, measure an input voltage of the powered device, andmeasure a current on the channel. The processor can be communicativelycoupled to the power sourcing equipment. The processor can determine theresistance of the channel based on the output voltage, the inputvoltage, and the current. The processor can determine, based on theresistance of the channel, an amount by which to increase a level ofpower provided to the powered device. The processor can output a commandto the power sourcing equipment to increase the level of power and theamount by which to increase the level of power.

These illustrative aspects and features are mentioned not to limit ordefine the invention, but to provide examples to aid understanding ofthe inventive concepts disclosed in this application. Other aspects,advantages, and features of the present invention will become apparentafter review of the entire disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a distributed antenna system in which aPoE system can be disposed according to one aspect.

FIG. 2 is a schematic diagram of a PoE system according to one aspect.

FIG. 3 is a block diagram of a computing device with code capable ofadjusting power loads of a powered device in a PoE system according toone aspect.

FIG. 4 is a flow chart illustrating a process for adjusting powerprovided to a powered device based on the channel resistance in a PoEsystem according to one aspect.

FIG. 5 is a flow chart illustrating a process for selectively providingpower to optional power loads of a powered device in a PoE systemaccording to one aspect.

FIG. 6 is a flow chart illustrating a process for balancing power loadsamong powered channel pairs in a PoE system according to one aspect.

FIG. 7 is a flow chart illustrating a process for adjusting powerprovided to a powered device based on the channel type in a PoE systemaccording to one aspect.

FIG. 8 is a schematic diagram of a PoE system according to a secondaspect.

DETAILED DESCRIPTION

Certain aspects and features of the present invention are directed to aPoE system for a distributed antenna system (“DAS”). A DAS can include amaster unit communicating telecommunication information between basestations or other equipment of cellular service providers and remoteantenna units distributed in an area and capable of wirelesslycommunicating with wireless devices. Power can be delivered via PoE frompower source equipment (“PSE”), which may be in a master unit, to apowered device (“PD”), which may be in a remote antenna unit.

A PoE system according to some aspects may also include a system foradjusting the power provided by a PSE to one or more PDs based on theresistance of a channel that includes an Ethernet cable coupling the PSEto one or more of the PDs. The PoE system can include hardware and/orsoftware for adjusting power supplied by the PSE. The hardware and/orsoftware for adjusting power supplied by the PSE may be disposed in thePSE, in the PD, or in an external controller. The PoE system may providemore power than contemplated by the IEEE standard by using both poweredpairs of an Ethernet cable and/or multiple Ethernet cables to providepower.

In some aspects, the amount of provided power can be adjusted based onthe quality of the channel that includes an Ethernet cable. For example,the PoE system can increase power provided to a PD in response todetermining that the resistance of the channel does not exceed athreshold resistance. In some aspects, the PoE system can configure thePD to be operated at full power in response to determining that theresistance of the channel does not exceed the threshold resistance. Inother aspects, the PoE system can selectively provide power to one ormore optional loads of the PD based on the resistance of the channel. Insome aspects, the PD can be powered off or operated in a “safe mode” ifthe resistance of the channel exceeds the threshold resistance.

In some aspects, the PoE system can balance power loads among poweredpairs. Balancing the power loads may include equalizing the powerprovided over powered pairs, equalizing the current on powered pairs, orequalizing the power loss across powered pairs.

Other aspects of a system for adjusting the power provided by a PSE toone or more PDs in a DAS can be implemented using other types of channelhaving a conductive material over which both power and data can betransported. For example, a system may include a PSE providing data andpower over a channel that includes a coaxial cable to the PD. Power canbe provided over the coaxial cable by providing current via the centerconductor of the coaxial cable and receiving return current via theshield conductor.

A “channel” includes one or more physical components that can transmitinformation from one network location to another network location.Examples of physical components that, individually or in combination,can form a channel include cables, cordage, patch panels, outlets,concentration points, other interfacing equipment, and any equipmentincluded in or related to a communications link. Cables can includeEthernet cables, coaxial cables, or other types of cables.

Detailed descriptions of these aspects are discussed below. Theseillustrative examples are given to introduce the reader to the generalsubject matter discussed here and are not intended to limit the scope ofthe disclosed concepts. The following sections describe variousadditional aspects and examples with reference to the drawings in whichlike numerals indicate like elements, and directional descriptions areused to describe the illustrative aspects but, like the illustrativeaspects, should not be used to limit the present invention.

FIG. 1 schematically depicts a DAS 10 in which a PoE system can bedisposed according to one aspect. The DAS 10 can be communicativelycoupled to at least one base station 12 via a wired or wirelesscommunication medium. The DAS 10 can be positioned in an area such as abuilding environment to extend wireless communication coverage.

The DAS 10 can include one or more remote antenna units 14 that aredistributed in the environment to provide coverage within a service areaof the DAS 10. The remote antenna units 14 can service a number ofdifferent user devices 16, such as cellular phones, operating in theenvironment of the DAS 10.

The remote antenna units 14 can be communicatively coupled to one ormore master units 22 via any communication medium capable of carryingsignals between the master unit 22 and remote antenna unit 14. Anon-limiting example of a suitable communication medium is an Ethernetcable. Master units 22 can process the signals from remote antenna units14 to interface appropriately with the base station 12. Although DAS 10is depicted as including two master units 22 and four remote antennaunits 14, any number (including one) of each of master units 22 andremote antenna units 14 can be used.

The PDs in a DAS 10, such as remote antenna units 14, can be poweredusing a PoE system. The PoE system can include components disposed inmaster units 22 and/or remote antenna units 14.

FIG. 2 depicts a functional block diagram of a PoE system 100 for use ina DAS 10 or other communication system according to one aspect. PoEsystem 100 may include PSE 102, a communication channel 104, and a PD106.

PSE 102 can include any device or system configured or otherwiseoperable to supply power to a PD 106 over one or more Ethernet cables.PSE 102 may include physical layer (“PHY”) devices 110, 120 and PSE portunits 108, 118. PSE port units 108, 118 can be coupled to PSE outputport 128.

PHY devices 110, 120 can be any physical layer device providing a datainterface to a communication network. A non-limiting example of a PHYdevice is an Ethernet physical transceiver. PHY devices 110, 120 canprovide data that is transported via communication channel 104. PHYdevices according to some aspects can also determine characteristics ofthe communication channel 104, such as the electrical length of thecommunication channel 104, and loss characteristics, such as loss overfrequency and the signal-to-noise ratio, of signals provided over thecommunication channel 104.

PSE port units 108, 118 can provide and control power on communicationchannel 104. PSE port units 108, 118 can be co-located in a singlecomponent or disposed in separate components. PSE port unit 108 mayinclude a PSE controller 113, a power source 114, Ethernet magnetics112, and a measurement device 160 a. PSE port unit 118 may include a PSEcontroller 123, a power source 124, Ethernet magnetics 122, and ameasurement device 160 b.

Power sources 114, 124 can provide the power to be transmitted to PD106. PSE controllers 113, 123 can adjust the power provided overcommunication channel 104 to PD 106. PSE controllers 113, 123 can alsoverify that a resistive load is available to receive power. Verifyingthat a resistive load is available can include determining whether ashort circuit exists in the communication channel 104. In some aspects,the PSE controllers 113, 123 can be disposed in a single component suchas a dual PSE controller. A dual PSE controller can be disposed in PSE102 and external to the PSE port units 108, 118.

Ethernet magnetics 112, 122 can provide both data from PHY devices 110,120 and power from PSE port units 108, 118 to communication channel 104.

PSE 102 can be connected to communication channel 104 via PSE outputport 128. PSE port unit 108 can be coupled to PSE output port 128 viatap connection 116. PSE port unit 118 can be coupled to PSE output port128 via tap connection 126. PSE output port 128 may be a PoE-enabledcommunication port. A non-limiting example of a PoE enabledcommunication port is an RJ-45 Ethernet interface port.

Communication channel 104 can be any type of channel over which bothpower and data can be provided. Examples components included in thecommunication channel 104 can include (but are not limited to) anEthernet cable such as category 5, category 5e, category 6, category 6A,or category 7 cables, coaxial cable, cordage, patch panels, outlets,concentration points, other interfacing equipment, and any equipmentincluded in or related to a communications link. Communication channel104 may include powered pairs 130, 136. Powered pair 130 can includewire pair 132 and wire pair 134. PSE port unit 108 can provide powerover powered pair 130 via tap connection 116. Powered pair 136 caninclude wire pair 138 and wire pair 140. PSE port unit 118 can providepower over powered pair 136 via tap connection 126.

PD 106 can receive power from PSE 102 via communication channel 104. PD106 and PSE 102 can also transmit and receive data via communicationchannel 104. Data can be transmitted over either or both of poweredpairs 130, 136. PD 106 may be a universal access point, such as a remoteantenna unit. PD 106 can include PD input port 142. PD input port 142can be a PoE-enabled communication port. PD 106 can be connected tocommunication channel 104 via PD input port 142.

In some aspects, PD 106 may include PD port units 148 a-b, power controlcircuitry 158, base load 150, one or more optional loads 152 a-b, andPHY device 156. PD port units 148 a-b can be coupled to PD input port142 via tap connections 144, 146. PD port units 148 a-b can also becoupled to power control circuitry 158.

PD port units 148 a-b may include magnetics 154 a-b and one or more PDcontrollers 159 a-b. Magnetics 154 a-b can be configured to receivepower and data from communication channel 104. PD port unit 148 a canuse magnetics 154 a to extract power from powered pair 130 via tapconnection 144. PD port unit 148 b can use magnetics 154 b to extractpower from powered pair 136 via tap connection 146.

PHY device 156 can receive and route the data extracted fromcommunication channel 104 by PD port unit 148 a. PHY device 156 can alsodetermine characteristics of the communication channel 104 and the losscharacteristics of signals provided over the communication channel 104.

The PD controllers 159 a-b can communicate with the power controlcircuitry 158 to determine whether the base load 150 or the optionalloads 152 a-b are available to receive power. PD controllers 159 a-b cancommunicate control messages to the PSE controllers 113, 123 to verifythat the resistive loads are present.

Power control circuitry 158 can receive and route the power extractedfrom communication channel 104. Power control circuitry 158 can controland provide power to base load 150 and optional loads 152 a-b. Powercontrol circuitry 158 can also convert between AC power and DC power.Providing power to base load 150 and optional loads 152 a-b can includeswitching power from PD port units 148 a-b between the base load 150 andoptional loads 152 a-b and balancing the power provided to the base load150 and optional loads 152 a-b.

Base load 150 can include the minimum circuitry functions for operatingPD 106. Optional loads 152 a-b can include one or more add-on componentsthat augment the capabilities of PD 106. For example, where PD 106 is aremote antenna unit, optional loads 152 a-b may be additional digitalsignal processing boards that extend the available frequency range ofthe remote antenna unit. Although PD 106 is depicted as including twooptional loads 152 a-b, any number (including one) of multiple optionalloads 152 a-b can be included in PD 106.

In some aspects, PD 106 can support one or more optional loads by one ormore pass-through communication ports. A pass-through communication portcan pass data and power to another PD. The power of the pass-throughcommunication port may be the full power received on one or both poweredpairs 130, 136, or a fraction of the total received power.

In the PoE system depicted in FIG. 2, PSE 102 can provide power overboth powered pairs 130, 136. In other aspects, PSE 102 can provide powerover a single communication channel 104 or PoE power can be providedover multiple communication channels. In a PoE system using both poweredpairs of a communication channel and/or multiple communication channels,PSE 102 can provide power of up to 100 watts or more.

PoE system 100 can also include a sub-system for measuring theresistance of communication channel 104 and adjusting the power providedto PD 106 based on the resistance. The sub-system may includemeasurement devices 160 a-b, 162 a-b, and computing device 164.

Measurement devices 160 a-b, 162 a-b may be any device or group ofdevices capable of measuring current and voltage. Measurement devices160 a-b, 162 a-b can include measurement bridges 161 a-b, 163 a-b. Eachmeasurement bridge can include one or more shunt resistors for measuringthe current on each wire pair. Examples of measurement devices caninclude (but are not limited to) onboard devices disposed in PSE 102 orPD 106, such as voltage and current sense amplifiers andanalog-to-digital converters. Other examples of measurement devices caninclude (but are not limited to) external devices such as a voltmeter, apotentiometer, an oscilloscope, and an ampere or current meter.

In some aspects, PSE controllers 113, 123 can provide data on the outputvoltage or current and PD controllers 159 a-b can measure input voltageand current, which may obviate the need for measurement devices 160 a-b,162 a-b.

Measurement devices 160 a-b can be disposed in PSE port units 108, 118and coupled to tap connections 116, 126, respectively. Measurementdevice 160 a can measure the voltage across tap connection 116 andcurrent at tap connection 116. Measurement device 160 b can measure thevoltage across tap connection 126 and current at tap connection 126. Themeasured voltages across tap connections 116, 126 can be used todetermine the combined voltage across PSE output port 128.

Measurement devices 162 a-b can be disposed in PD port units 148 a-b andcoupled to tap connections 144, 146, respectively. Measurement device162 a can measure the voltage across tap connection 144 and current attap connection 144. Measurement device 162 b can measure the voltageacross tap connection 146 and current at tap connection 146. Themeasured voltages across tap connections 144, 146 can be used todetermine the combined voltage across PD input port 142.

Computing device 164 can be communicatively coupled to measurementdevices 160 a-b, 162 a-b, PD 106, and PSE 102. Although computing device164 is depicted as being disposed in PD 106, computing device 164 canalternatively be disposed in PSE 102 or in an external device. Computingdevice 164 can adjust power provided to PD 106 based on the resistanceof communication channel 104. FIG. 3 depicts a block diagram of acomputing device 164 for adjusting power provided to PD 106 according toone aspect. Computing device 164 may be any device that can process dataand execute code that is a set of instructions to perform actions. Insome aspects, the computing device 164 is a simple device that providesan alarm based on a given threshold to perform power adjustments viasoftware or directly via hardware. The threshold may be hardwire oradjustable, such as via software. The computing device 164 may be partof the measurement device 162 instead of a separate component.

The computing device 164 includes a processor 202 that can execute codestored on a computer-readable medium, such as a memory 204, to cause thecomputing device 164 to manage power provided to PD 106. Examples ofprocessor 202 include a microprocessor, an application-specificintegrated circuit (“ASIC”), a field-programmable gate array (“FPGA”),or other suitable processor. The processor 202 may include one processoror any number of processors.

Processor 202 can access code stored in memory 204 via a bus 206. Memory204 may be any non-transitory computer-readable medium capable oftangibly embodying code and can include electronic, magnetic, or opticaldevices. Examples of memory 204 include random access memory (“RAM”),read-only memory (“ROM”), magnetic disk, an ASIC, a configuredprocessor, or other storage device. Bus 206 may be any device capable oftransferring data between components of the computing device 164. Bus206 can include one device or multiple devices.

Instructions can be stored in memory 204 as executable code. Theinstructions can include processor-specific instructions generated by acompiler and/or an interpreter from code written in any suitablecomputer-programming language, such as C, C++, C#, Visual Basic, Java,Python, Perl, JavaScript, and ActionScript.

The instructions can include a power management engine 210. The powermanagement engine 210 can be executed by the processor 202 to cause thecomputing device 164 to adjust power provided to PD 106, as explained inmore detail below. The computing device 164 can receive inputs viainput/output (“I/O”) interface 208. The computing device 164 can storedata representing such inputs in memory 204. Examples of such inputs caninclude measurements received from measurement devices 160 a-b, 162 a-band a type of channel for the communication channel 104. In someaspects, the type of channel for the communication channel 104 can bereceived via a graphical interface displayed on a separate computingdevice or on a display associated with the computing device 164. Varioustypes of data for various channel types can be stored as a data file inmemory 204. Using the type of channel for the communication channel, thepower management engine 210 can determine data, such as resistivity andcross-sectional area, about the communication channel 104 from theassociated data in memory 204. The power management engine 210 candetermine, and store in memory 204, a length of the communicationchannel 104 based on data received from a physical layer device and thetype of channel. Power management engine 210 can determine the length bydividing the resistivity of communication channel 104 by the product ofthe resistance and cross-sectional area of communication channel 104.The power management engine 210 can determine temperature for thecommunication channel 104 based on the length, voltage measurements, andcurrent measurement. The temperature for the communication channel 104can be stored in memory 204.

Power management engine 210 can also determine the total resistance ofcommunication channel 104 or the individual resistances of powered pairs130, 136. Power management engine 210 can also determine whether theresistance exceeds a predetermined threshold and adjust the powerprovided to PD 106 accordingly. Power management engine 210 can generatecontrol signals for computing device 164 to transmit to PSE 102 and/orPD 106.

Memory 204 can also include threshold data 212. Threshold data 212 maybe a data file. Threshold data 212 can include information on theacceptable resistance for a communication channel 104 based on the powerrequirements of various PDs 106. Threshold data 212 can also includeother information related to the safe operation of the PoE system, suchas the acceptable operating temperature of communication channel 104. Insome aspects, threshold data 212 can be stored separately from thecomputing device 164 in a computer-readable medium accessible by thecomputing device 164 via the I/O interface 208.

Memory 204 can also include load data 214. Load data 214 may be a datafile. Load data 214 can include information on the power requirementsfor base load 150 and optional loads 152 a-b in PD 106. Load data 214can include a priority for each of optional loads 152 a-b specifying theorder in which to activate each of the optional loads 152 a-b. In someaspects, load data 214 can be stored separately from the computingdevice 164 but in communication with the computing device 164 throughI/O interface 208.

In some aspects, the processor 202 can execute the power managementengine 210 to determine a channel resistance based on an impedance inthe PD. For example, the impedance in the PD may be known and thecurrent and voltage in the PSE can be measured. Power level and loadallocation decisioning can be performed based on the determined channelresistance based on the known impedance in the PD.

This exemplary system configuration is provided to illustrateconfigurations of certain aspects. Other configurations and aspects mayof course be utilized. For example, a PoE system according to someaspects may be implemented using a single PD controller and measurementdevice. FIG. 8 schematically depicts a PoE system that includes a singlePD controller 159, a single measurement device 163, and a singlemeasurement bridge. The PoE system is otherwise similar to the PoEsystem depict in FIG. 2, except that tap connections 144, 146 in FIG. 2are joined together as tap connection 147 in FIG. 8. The PoE system inFIG. 8 may be configured to provide a threshold alarm at the PD 106indicating the presence of a possible problem, such as high temperatureor power overload problems. The computing device 164 can respond to thealarm condition, and may adjust threshold levels. This process may beautonomously implemented and the computing device 164 may not berequired to react to problems with power of the channel.

FIG. 4 depicts a flow chart illustrating a process for adjusting powerprovided to a PD according to certain aspects of the present invention.The process is described with reference to the PoE system 100 depictedin FIG. 2 and the system implementation shown in FIG. 3. Otherimplementations and processes, however, are possible.

In block 302, power management engine 210 configures PSE 102 to providepower to PD 106 over communication channel 104. In some aspects, thepower from PSE 102 may not exceed the maximum power provided in PoEsystems as specified according to standardized PoE protocols. Forexample, the level of power provided over communication channel 104 maybe less than full power or a minimal power level at which the quality ofthe communication channel 104 can be assessed.

In block 304, the power management engine 210 receives measurements frommeasurement devices. The measurements can include the voltage at PSEoutput port 128 from measurement devices 160 a-b, the voltage at PDinput port 142 from measurement devices 162 a-b, and the current oncommunication channel 104 from measurement devices 160 a-b or 162 a-b.In some aspects, measurement devices 160 a-b, 162 a-b may be disposed inPSE 102 and/or PD 106, as depicted in FIG. 2. In other aspects, themeasurement devices may be disposed in devices external to PSE 102 andPD 106.

In block 306, power management engine 210 determines the resistance ofcommunication channel 104. The resistance can be determined, forexample, by dividing the difference in voltages at PSE output port 128and PD input port 142 by the current on communication channel 104. Inother aspects, a measurement device can measure the resistance of thecommunication channel 104 and the power management engine 210 canreceive the resistance from the measurement device. Examples of ameasurement device can include (but are not limited to) onboard devices,such as voltage and current sense amplifiers and analog-to-digitalconverters, disposed in PSE 102 or PD 106. A measurement device canalternatively be a device external to PSE 102 or PD 106, such as anohmmeter.

In block 308, power management engine 210 determines whether theresistance of communication channel 104 exceeds an acceptable thresholdresistance for safely increasing power to PD 106. For example, powermanagement engine 210 can access threshold data 212 to identify theacceptable threshold resistance. In some aspects, the threshold data 212is a table that can include resistances associated with various types ofchannels and with ranges of acceptable power levels. Power managementengine 210 can access the threshold data 212 to identify the thresholdresistance for the type of channel of the communication channel 104. Thepower management engine 210 can compare the resistance determined forthe communication channel 104 to the threshold resistance for the typeof channel of the communication channel 104. The threshold resistancemay be the channel resistance for a channel type at which a maximumpower level can be safely carried, as specified in threshold data 212.

In other aspects, the power management engine 210 determines whether aresistance of the communication channel 104 exceeds a threshold bydetermining, based on the resistance and the channel type, whether amaximum power level of power would cause the temperature of thecommunication channel 104 to exceed an acceptable temperature, asspecified in threshold data 212. In some aspects, the power managementengine 210 can determine the channel temperature from the length and thecurrent and voltage difference across communication channel 104.

If the resistance of communication channel 104 exceeds an acceptablethreshold resistance, power management engine 210 determines if theresistance of communication channel 104 is low enough for PD 106 tooperate in a “safe” mode in block 310. Power management engine 210 canaccess threshold data 212 to identify the acceptable resistance for PD106 to operate in safe mode and compare the actual resistance of thecommunication channel 104 to the acceptable resistance. When PD 106operates in the safe mode, PSE 102 provides only enough power to operatePD port units 148 a-b.

If the resistance of communication channel 104 is not low enough for PD106 to operate in a safe mode, PSE 102 can cease providing power to PD106 in block 312. Power management engine 210 can configure PSE 102 tocease providing power by generating control signals that computingdevice 164 can transmit to PSE 102. An alarm or other type ofnotification can be outputted to notify that PSE 102 ceased providingpower and to provide information about possible problems with the systemthat caused the PSE 102 to cease providing power.

If the resistance of communication channel 104 is low enough for PD 106to operate in a safe mode, PSE 102 can provide sufficient power for safemode operation in block 314. Power management engine 210 can configurePSE 102 to provide sufficient power for safe mode operation bygenerating control signals that computing device 164, if disposed in PD106, can transmit to PSE 102. Power management engine 210 can configurePD 106 to operate in safe mode by generating control signals thatcomputing device 164 can provide to PD 106 as data in Ethernet packets.A notification can be outputted to notify that the system is operatingin safe mode with, optionally, an explanatory statement as to why thesystem is operating in safe mode.

If the resistance of communication channel 104 does not exceed anacceptable threshold resistance, power management engine 210 determinesthe amount of power that can safely be provided to the PD 106 in block316. For example, power management engine 210 can reference thresholddata 212 to determine the maximum power level for the resistance ofcommunication channel 104. Threshold data 212 can include information onthe maximum power level for a determined resistance of communicationchannel 104. The maximum power level can be the amount of power at whichthe communication channel 104 can carry power safely to the PD 106.

In block 318, the power management engine 210 can determine the amountof power to be provided to the PD 106. The amount of power to beprovided to the PD 106 can depend on the power load requirements in thePD 106 and the amount of power that the communication channel 104 cansafely carry to PD 106 (i.e., the maximum power level). The powermanagement engine 210 can determine the amount of power to be providedto the PD 106 using various methods. In one aspect, the power managementengine 210 accesses a table of levels stored in memory 204 that includea power requirement for a type of PD 106 coupled to the communicationchannel 104, and compares the power requirement to the maximum powerlevel to ensure that the maximum power level is greater than the powerrequirement. In other aspects, and as discussed in detail with respectto FIG. 5, the power management engine 210 determines the amount ofpower to be provided to the PD 106 by the PD 106 selectively activatingoptional loads, as limited by the maximum power level, and communicatinginformation associated with the optional loads to the power managementengine 210.

In some aspects, power management engine 210 can select a predeterminedmaximum power supplied by PSE 102 as the amount of power to be providedto the PD 106, or limit the amount of power to the maximum powerrequirement of PD 106. The maximum power requirement of PD 106 can bedetermined by referencing load data 214. The maximum power requirementof PD 106 may be the combined power requirements of base load 150 andall optional loads 152 a-b. Power management engine 210 can selectbetween the power levels based on whether either will exceed the maximumpower level for the resistance of communication channel 104, asspecified in threshold data 212. The power management engine 210 mayalso display a suggested or needed power level to a technicianresponsible for manually configuring the power level.

In block 320, power management engine 210 configures PSE 102 to increasepower to PD 106 by the amount determined in block 318. Power managementengine 210 can configure PSE 102 to provide the amount of powerdetermined in block 318 to PD 106 by generating control signals thatcomputing device 164 can transmit to PSE 102. Computing device 164, ifdisposed in PD 106, can communicate the control signal to PSE 102 aspacketized data provided over the powered pair 130, 136 used for datacommunication. Power management engine 210 can also generate a controlsignal to activate PD 106. In other aspects in which computing device164 is disposed in the PSE 102, the power management engine 210 canoutput controls signals to the PSE 102 and output a control signal, thatis provided as data in an Ethernet packet, to PD 106.

In some aspects, power management engine 210 can configure PSE 102 todetermine whether a resistive load, such as base load 150 or optionalloads 152 a-b, is detected prior to executing blocks 304 through 310.PSE controllers 113, 123 can communicate with PD controllers 159 a-b todetermine whether a resistive load is available to receive power fromPSE 102. PSE controllers 113, 123 can communicate with PD controllers159 a-b using Ethernet data packets provided over communication channel104. If PSE controllers 113, 123 are unable to establish a data linkwith one of the PD controllers 159 a-b, PSE controllers 113, 123 maydetermine that a short circuit exists in one or more of powered pairs130, 136 of communication channel 104. If a short circuit exists in oneof the powered pairs, blocks 304 through 320 may be executed using thepowered pair 130, 136 that does not include the short circuit, ratherthan the entire communication channel 104.

As noted above, FIG. 5 depicts a process according to some aspects fordetermining an amount of power to be provided to the PD 106. In block400 of FIG. 5, power management engine 210 determines the amount ofpower required to activate base load 150. Power management engine 210can determine the power requirements of base load 150 by referencingload data 214. Load data 214 can include information on the powerrequirements for base load 150.

In block 402, power management engine 210 identifies the optional load152 a-b with the highest priority. Optional loads 152 a-b can be one ormore digital signal processing boards that extend the availablefrequency range of the remote antenna unit. Power management engine 210can reference load data 214 to determine the priority of optional loads152 a-b. Load data 214 can include the power requirements and associatedpriority for each optional load 152 a-b. The priority of each optionalload 152 a-b may depend on the frequency ranges needed for a particularcoverage area of DAS 10. The frequency ranges needed for a particularcoverage area of DAS 10 may depend on the expected number of userdevices using a particular frequency that are operated within thecoverage area. The power requirements of each optional load 152 a-b cancorrespond to the complexity of the processing circuitry required toextend the frequency range of a remote antenna unit.

In block 404, power management engine 210 determines whether PSE 102 cansafely provide sufficient power to the identified optional load 152 a-bwith the highest priority. Power management engine 210 can determinewhether PSE 102 can safely provide additional power by comparing thepower required by the base load and the optional load having the highestpriority to the maximum power level determined for the communicationchannel 104. In some aspects, PSE 102 is unable to provide power safelyto the identified optional load 152 a-b if the total power provided oncommunication channel 104 would exceed the maximum power level. Thetotal power can be the combined power requirements of base load 150 andthe identified optional load 152 a-b having the highest priority.

If the PSE 102 can safely provide sufficient power to the identifiedoptional load 152 a-b with the highest priority, power management engine210 selects the identified optional load 152 a-b for activation in block406. Power management engine 210 can generate a control signal forcomputing device 164 to provide to PD 106 to activate the identifiedoptional load 152 a-b with the highest priority. Power management engine210 can also generate a command to PSE 102 to increase power to a powerlevel that can power the base load 150 and the identified optional load152 a-b having the highest priority to activate the identified optionalload 152 a-b. Computing device 164, if disposed in PD 106, cancommunicate the command to PSE 102 as Ethernet packets provided over thepowered pair 130, 136 used for data communication. In other aspects, thecomputing device 164 is disposed in the PSE 102 and can control the PSE102 using control signals.

In block 408, power management engine 210 determines whether anotheroptional load 152 a-b with a lower priority is available, either afterdetermining that it is unsafe to operate a higher priority optional loadin block 404 or after activating the higher priority optional load inblock 406. Power management engine 210 can determine if an optional load152 a-b with a lower priority is available by referencing load data 214to identify any optional loads 152 a-b not yet selected for activationand priorities associated with those optional loads 152 a-b.

If an optional load 152 a-b with a lower priority is available, powermanagement engine 210 identifies the optional load 152 a-b with the nexthighest priority in block 410. Power management engine 210 can referenceload data 214 to determine which of the inactive optional loads 152 a-bidentified in block 408 has the next highest priority. The processreturns to block 404 to determine iteratively whether the optional loadhaving the next highest priority can be safely activated based on theresistance of communication channel 104 and the total power of the baseload 150, any activated optional loads, and the optional load having thenext highest priority. This process may continue until no optional loadsare available for which the communication channel 104 can carry theadditional power needed to activate.

If no optional load 152 a-b with a lower priority is available for whichpower can be safely carried by communication channel 104, powermanagement engine 210 does not select any additional optional loads 152a-b for activation in block 412. The PSE 102 can provide power at apower level that is configured in block 406, or in block 400 if nooptional loads are present or if no optional loads are present for whichthe communication channel 104 can carry the additional power needed toactivate.

Balancing Power Among Channel Pairs

PSE port units 108, 118 can provide power to a common PD 106independently of one another. In some aspects, PoE system 100 canbalance the power provided over powered pairs 130, 136 to coordinate theoperation of PSE port units 108, 118. FIG. 6 depicts a flow chartillustrating a process for balancing power loads according to oneaspect. The process is described with reference to the PoE system 100depicted in FIG. 2 and the system implementation shown in FIG. 3. Otherimplementations and processes, however, are possible.

In block 502, power management engine 210 configures PSE 102 to providepower to PD 106 over each powered pair 130, 136. Power management engine210 may configure PSE 102 to provide power over each powered pair 130,136 by generating control signals that computing device 164 can transmitto PSE 102. In some aspects, the power provided over each powered pair130, 136 may not exceed the maximum power provided in PoE systems asspecified according to standardized PoE protocols.

In block 504, measurement devices 160 a-b, 162 a-b measure the inputvoltages at tap connections 116, 126 and the output voltages at tapconnections 116, 126, 144, 146. Measurement devices 160 a-b, 162 a-bmeasure the current on each powered pair 130, 136.

In block 506, power management engine 210 determines the resistance ofeach powered channel pair 130, 136. The resistance of each powered paircan be determined by dividing the voltage difference between respectivetap connections by the current on respective powered pair.

In block 508, power management engine 210 determines which powerbalancing scheme to apply. The power schemes may include power loadbalancing, current balancing, and power loss balancing. In some aspects,power management engine 210 can be pre-configured to select a givenpower-balancing scheme. In other aspects, power management engine 210may provide the resistances of powered pairs 130, 136 to a user devicecommunicatively coupled to computing device 164. Power management engine210 may receive from a user input a selection of a power managementscheme through the user device.

If power load balancing is determined to be the power scheme applied,power management engine 210 causes the power load among powered pairs130, 136 to be balanced in block 510. For example, power managementengine 210 can configure PSE port units 108, 118 to provide equal powerover each powered pair 130, 136 such that each powered pair carries halfof the power to be provided by the PSE port units 108, 118. The poweredpair with a lower resistance may dissipate less power compared to thepowered pair with higher resistance. Although lower in total efficiencycompared to the other power balancing schemes, balancing the power loadcan simplify the control of powered pairs 130, 136 with respect to eachother. After power management engine 210 applies the power managementscheme, power management engine 210 can configure power controlcircuitry 158 to distribute the power received from each powered pairamong the base load 150 and optional loads 152 a-b.

If current balancing is determined to be the power scheme applied, powermanagement engine 210 causes the current among powered pairs 130, 136 tobe balanced in block 512. For example, power management engine 210 canconfigure PSE port units 108, 118 to provide equal current over eachpowered pair 130, 136. At a given power requirement for PD 106, abalanced current flow for each powered pair 130, 136 can dissipate lesspower over the powered pair with lower resistance compared to thepowered pair with higher resistance. As with power load balancing,balancing the current can simplify the control of powered pairs 130, 136with respect to each other. After power management engine 210 appliesthe power management scheme, power management engine 210 can configurepower control circuitry 158 to distribute the power received from eachpowered pair among the base load 150 and optional loads 152 a-b.

If power loss balancing is determined to be the power scheme applied,power management engine 210 balances the power loss among powered pairs130, 136 in block 514. The power loss of each powered pair 130, 136 isthe voltage difference across the powered pair multiplied by the currenton each powered pair. Power management engine 210 can configure PSE portunits 108, 118 to adjust current over each powered pair 130, 136 toequalize power loss for each powered pair. Balancing the power lossamong powered pairs 130, 136 can minimize the total power loss ofcommunication channel 104. After power management engine 210 applies thepower management scheme, power management engine 210 can configure powercontrol circuitry 158 to distribute the power received from each poweredpair among the base load 150 and optional loads 152 a-b.

FIG. 7 illustrates a process for adjusting power provided to a PD basedon the channel type of communication channel 104 in the PoE system ofFIGS. 2 and 3 according to one aspect. The process can be used todetermine the maximum power that can be safely provided over acommunication channel of a determined channel type used in the PoEsystem, without determining the channel resistance from the measurementsof voltage and current. The PoE system can determine whether to increasepower or to cease operating, as in the process depicted in FIG. 4.

In block 602, power management engine 210 configures PSE 102 to providepower to PD 106 over communication channel 104. In some aspects, thepower from PSE 102 may not exceed the maximum power provided in PoEsystems as specified according to standardized PoE protocols. Forexample, the level of power provided over communication channel 104 maybe less than full power or otherwise at some minimal power level atwhich the quality of the communication channel 104 can be assessed.

In block 604, the power management engine 210 receives the electricallength and loss characteristics of communication channel 104. In someaspects, PHY 156 can determine the electrical length and losscharacteristics and provide them to power management engine 210. Inother aspects, computing device 164 may communicate with PSE 102 viacommunication channel 104 to request that PHY devices 110, 120 determinethe electrical length and loss characteristics for PSE 102 and providethem to power management engine 210 via computing device 164. Computingdevice 164, if disposed in PD 106, can communicate the request to PSE102 as Ethernet packets provided over the powered pair 130, 136 used fordata communication.

In block 606, power management engine 210 determines the channel type ofcommunication channel 104 using the electrical length and losscharacteristics of the channel. Power management engine 210 candetermine the channel type by accessing a data file stored in memory204. The data file can include various types of data, such as theelectrical length and loss characteristics of the channel, for variouschannel types. Power management engine 210 can compare the electricallength and loss characteristics of communication channel 104 to thevarious electrical lengths and loss characteristics in the data file andidentify the corresponding channel type.

In block 608, power management engine 210 determines the amount of powerthe communication channel 104 can safely carry based on the channeltype. In some aspects, a data file stored in memory 204 can include atable that can include ranges of acceptable power levels that can beprovided over various types of channels. Power management engine 210 canaccess the data file to determine the acceptable ranges of power thatcan be provide over the channel type for the communication channel 104.

The power management engine 210 can determine whether to increase thepower based on the amount of power that can be safely transported overthe communication channel 104. If the power cannot be safely increased,the power management engine 210 can determine if enough power can besafely provided over the communication channel 104 for the PD 106 tooperate in a “safe” mode, as in block 310 of the process depicted FIG.4. The power management engine 210 can access a data file stored inmemory 204 to determine whether the maximum power provided over thechannel type for communication channel 104 can support safe modeoperation. If enough power cannot be safely provided over thecommunication channel 104 for the PD 106 to operate in a safe mode, thepower management engine 210 can configure the PSE 102 to cease providingpower to PD 106, as in block 312 of the process depicted FIG. 4. Ifenough power can be safely provided over the communication channel 104for the PD 106 to operate in a safe mode, PSE 102 can provide sufficientpower for safe mode operation as in block 314 of the process depictedFIG. 4. If the power can be safely increased, the power managementengine 210 can determine the amount of power to be provided to the PD106 and increase power accordingly, as in blocks 318-320 of the processdepicted FIG. 4.

Although aspects have been described with respect to channels thatinclude cables that are Ethernet cables and Ethernet protocols, thesystems and processes described above can be implemented using one ormore channels having any suitable cable having at least one conductivematerial over which both electrical energy, such as power and signalsrepresenting data, can be provided.

For example, a system may include a PSE coupled to a PD over acommunication channel that includes a coaxial cable. The PSE can providedata and power over the coaxial cable to the PD. The coaxial cable caninclude an electrical cable with a center conductor, a tubularinsulating layer disposed radially exterior to the center conductor, anda tubular shield conductor disposed radially exterior to the tubularinsulating layer. The coaxial cable can receive data from a PHY device.Power can be provided over the coaxial cable by providing current from apower source to the center conductor and receiving return current viathe shield conductor. Current can be provided to the center conductorvia a device such as a bias T. In this aspect, the bias T can replacemagnetics used to provide power to the powered pairs of an Ethernetcable.

In another aspect, the system may include a communication channel thatincludes an optical fiber and a parallel power channel that includes anelectrical cable. The optical fiber can carry data and the electricalcable can carry power. The optical fiber can receive data from the PHYdevice. The electrical cable can be connected to a PSE controller orpower supply, which may obviate the need for a separate component, suchas magnetics or a bias T.

The foregoing description of the aspects, including illustrated aspects,of the invention has been presented only for the purpose of illustrationand description and is not intended to be exhaustive or to limit theinvention to the precise forms disclosed. Numerous modifications,adaptations, and uses thereof will be apparent to those skilled in theart without departing from the scope of this invention.

1. A system comprising: a powered device configured for receiving powerfrom a power source device via a channel, the powered device comprisinga base load and one or more optional loads; and a sub-system configuredfor: determining the power capabilities of the channel, determining arespective power requirement for each of the one or more optional loads,and based on the power capabilities of the channel and the respectivepower requirements for the one or more optional loads, configuring thepowered device to operate the base load and all or a subset of the oneor more optional loads.
 2. The system of claim 1, wherein the sub-systemis at least partially disposed in the powered device and whereinconfiguring the powered device to operate the base load and all or thesubset of the one or more optional loads comprises configuring powercontrol circuitry of the powered device to route the power received viathe channel to the base load and all or the subset of the one or moreoptional loads.
 3. The system of claim 1, wherein the sub-system is atleast partially disposed in a master unit of a distributed antennasystem and wherein configuring the powered device to operate the baseload and all or the subset of the one or more optional loads comprisestransmitting, via the channel, a control signal for activating the baseload and all or the subset of the one or more optional loads to a remoteantenna unit of the distributed antenna system, wherein the remoteantenna unit comprises the powered device.
 4. The system of claim 1,wherein the channel comprises at least one physical component configuredfor transmitting information from one network location to a secondnetwork location, the at least one physical component comprising atleast two of a cable, cordage, a patch panel, an outlet, or aconcentration point.
 5. The system of claim 4, wherein the powereddevice is further configured to communicate data with the power sourcedevice via the channel.
 6. The system of claim 1, wherein the sub-systemcomprises: at least one measurement device configured for: measuring anoutput voltage of the power source device; measuring an input voltage ofthe powered device; measuring a current on the channel; a processorconfigured for determining the power capabilities of the channel basedon the output voltage, the input voltage, and the current measured bythe at least one measurement device.
 7. The system of claim 1, whereinthe base load comprises a minimum amount of circuitry required foroperating the powered device.
 8. The system of claim 7, wherein thepowered device is a remote antenna unit of a distributed antenna systemand each of the one or more optional loads comprises a signal processingdevice associated with a respective frequency range for the remoteantenna unit.
 9. The system of claim 1, wherein the sub-system isfurther configured for determining that increasing the power providedvia the channel is unsafe based on comparing the power capabilities ofthe channel to a threshold, wherein the threshold is associated with atemperature increase that exceeds a threshold temperature indicative ofan overall power loss in the channel that exceeds a safe level.
 10. Thesystem of claim 1, wherein the sub-system is further configured fordetermining, based on the power capabilities of the channel, a safelevel of power to the powered device, wherein the safe level of powercomprises an amount of power sufficient to operate one or morecomponents of the powered device configured to receive signals via thechannel.
 11. The system of claim 1, wherein the channel comprises atleast two powered pairs over which the power source device is configuredto provide the power to the powered device, wherein the sub-system isfurther configured for: determining a respective power capability ofeach of the at least two powered pairs, and equalizing power dissipationover each of the at least two powered pairs based on the respectivepower capability of each powered pair.
 12. A method, comprising:determining, by a processor, a power capability of a channel used forproviding power from a power source device to a powered device, thepowered device comprising a base load and one or more optional loads;and determining, by the processor, a respective power requirement foreach of the one or more optional loads; and based on the powercapability of the channel and the respective power requirements for theone or more optional loads, configuring the powered device to operatethe base load and all or a subset of the one or more optional loads. 13.The method of claim 12, wherein configuring the powered device tooperate the base load and all or a subset of the one or more optionalloads comprises configuring power control circuitry to route the powerreceived via the channel to the base load and all or a subset of the oneor more optional loads.
 14. The method of claim 12, wherein configuringthe powered device to operate the base load and all or a subset of theone or more optional loads comprises transmitting, via the channel, acontrol signal for activating the base load and all or a subset of theone or more optional loads to a remote antenna unit of a distributedantenna system, wherein the remote antenna unit comprises the powereddevice.
 15. The method of claim 12, wherein the powered device isfurther configured to communicate data with the power source device viathe channel.
 16. The method of claim 12, wherein the base load comprisesa minimum amount of circuitry required for the powered device tooperate.
 17. The method of claim 16, wherein the powered device is aremote antenna unit of a distributed antenna system and each of the oneor more optional loads comprises a signal processing device associatedwith a respective frequency range for the remote antenna unit.
 18. Themethod of claim 12, further comprising determining that increasing thepower provided via the channel is unsafe based on comparing the powercapability of the channel to a threshold, wherein the threshold isassociated with a temperature increase that exceeds a thresholdtemperature indicative of an overall power loss in the channel thatexceeds a safe level.
 19. The method of claim 12, further comprisingdetermining, based on the power capability of the channel, a safe levelof power to the powered device, wherein the safe level of powercomprises an amount of power sufficient to operate one or morecomponents of the powered device configured to receive signals via thechannel.
 20. The method of claim 12, wherein the channel comprises atleast two powered pairs over which the power source device is configuredto provide the power to the powered device, and further comprising:determining a respective power capability of each of the at least twopowered pairs, and equalizing power dissipation over each of the atleast two powered pairs based on the respective power capability of eachpowered pair.